#define CALC_API extern "C" __declspec(dllexport)

CALC_API void MultiplyMatricesDoublePlain(int size, double* m1[], double* m2[], double* result[])
 {  
   for (int i = 0; i < size; i++)  
   {  
     for (int j = 0; j < size; j++)  
     {  
       result[i][j] = 0;

       for (int k = 0; k < size; k++)  
       {  
         result[i][j] += m1[i][k] * m2[k][j];
       }  
     }  
   }  
 }